Abdominal compliance: A bench-to-bedside review

Abdominal compliance is an important determinant and predictor of available workspace during laparoscopic surgery. Furthermore, critically ill patients with a reduced abdominal compliance are at an increased risk of developing intra-abdominal hypertension and abdominal compartment syndrome both of which are associated with high morbidity and mortality. Despite of this, abdominal compliance is a concept, which has been neglected in the past. Abdominal compliance is defined as a measure of the ease of abdominal expansion, expressed as a change in intra-abdominal volume per change in intra-abdominal pressure: abdominal compliance = delta intra-abdominal volume / delta intra-abdominal pressure. AC is a dynamic variable, dependent on base-line IAV and IAP as well as reshaping and stretching capacity. Whereas abdominal compliance itself can only rarely be measured, it always needs to be considered an important component of intra-abdominal pressure. Patients with decreased abdominal compliance are prone to fulminant development of abdominal compartment syndrome when concomitant risk factors for intra-abdominal hypertension are present. This review aims to clarify the pressure-volume relationship within the abdominal cavity. It highlights how different conditions and pathologies can affect abdominal compliance and which management strategies could be applied to avoid serious consequences of decreased abdominal compliance. We have pooled all available human data to calculate abdominal compliance values in patients acutely and chronically exposed to intra-abdominal hypertension and demonstrated an exponential abdominal pressure-volume relationship. Most importantly, patients with high level of intra-abdominal pressure have a reduced abdominal compliance. In these patients, only small reduction in intra-abdominal volume can significantly increase abdominal compliance and reduce intra-abdominal pressures. A greater knowledge on abdominal compliance may help in selecting a better surgical approach as well as reducing complications related to intra-abdominal hypertension

Enteral nutrition in the critically ill: A prospective survey in an Australian intensive care unit

Publisher's copy made available with the permission of the publisher © Australian Society of AnaesthetistsNutritional support is routine practice in critically ill patients and enteral feeding is preferred to the parenteral route. However this direct delivery of nutrients to the gut is potentially ineffective for a variety of reasons. We performed a prospective audit of 40 consecutive intensive care patients to determine whether enteral feeding met the nutritional requirements of our patients. The ideal requirements for each patient were calculated using the Harris-Benedict equation with an adjustment determined by the patient’s diagnosis. We compared the amount of feed delivered with the daily requirements over a seven-day period. Successful feeding was defined as the achievement of 90% of the ideal calorie requirement for two consecutive days. The mean calculated (±SD) energy requirement was 9566kJ (±2586). Patients received only 51% (SD 38) of their energy requirements throughout the study period. Only 10 patients (25%)were successfully fed for at least any two-day period in the seven days. Feeding was limited mainly by gastrointestinal dysfunction or by the need to fast the patient for medical, surgical and airway procedures. Success of feeding was not related to the use of sedative or paralysing agents and had no correlation with plasma albumin concentration. There was no difference in the volume of feed delivered to patients who survived or died. Prokinetic agents were used in 25 patients and in these patients there was a trend towards improved delivery of feed.I. De Beaux, M. Chapman, R. Fraser, M. Finnis, B. De Keulenaer, D. Liberalli, M. Satanekhttp://www.aaic.net.au/Article.asp?D=200111

The effect of non-invasive ventilation on intra-abdominal pressure

Background: Non-invasive ventilation is a well-established treatment modality in patients with respiratory failure of different aetiologies. A previous case report described how non-invasive ventilation caused gastric distension and intra-abdominal hypertension with subsequent cardio-respiratory arrest and clinical recovery following resuscitative efforts including gastric decompression with a nasogastric tube. Methods: The aim of this prospective multicentre observational study was to assess the effect of non-invasive ventilation on intra-abdominal pressure. Following informed consent, intra-abdominal pressure and PaCO2were measured before and after the application of non-invasive ventilation for up to three days in critically ill patients requiring non-invasive ventilation. Results: Thirty-five patients were enrolled; mean (±SD) age of 67.8 (±12.5) years, median (interquartile range) body mass index of 27.9 (24.5-30.0) kg m-2, Acute Physiology and Chronic Health Evaluation II score of 15.8 (±6.4). On admission and after 24 hours of non-invasive ventilation, intra-abdominal pressure was 11.0 (7.5-15.0) mm Hg and 11.0 (8.5-14.5) mm Hg (P = 0.82) and PaCO2was 44.4 (±11.4) mm Hg and 51.3 (±14.3) mm Hg (P = 0.19), respectively. Conclusions: The application of non-invasive ventilation was not associated with an increase in intra-abdominal pressure over 72 hours in this small observational study. Thus, it appears that intra-abdominal pressure does not frequently increase when applying non-invasive ventilation in critically ill patients with respiratory failure

Spatial division multiplexing for optical data center networks

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